Emotion regulation group therapy (ERGT) is a novel treatment specifically targeting deliberate non-suicidal self-harm (DSH) in individuals with borderline personality disorder (BPD). Identifying robust predictors of positive response to ERGT could aid clinicians in treatment selection; however, to date, only one such study has been conducted. Thus, we aimed to replicate previously identified predictors of treatment response to ERGT by investigating demographic, clinical, and diagnostic predictors in 95 women with BPD or subclinical BPD who had participated in an open-trial evaluation of ERGT. Outcomes evaluated were frequency of DSH and emotion dysregulation. Assessments were conducted at pretreatment, post-treatment, and 6-month follow-up. Multilevel mixed linear models and multilevel negative binomial generalized estimated equations were used to identify significant interactions between the predictors and outcomes.
We found that greater pretreatment DSH frequency was associated with greater improvements in DSH during treatment (b = 0.998, SE = 0.00, p = 0.03) and follow-up (b = 0.997, SE = 0.00, p < 0.01) and that greater BPD severity was associated with greater improvements in DSH during treatment (b = 0.84, SE = 0.06, p = 0.02) and in emotion dysregulation at follow-up (b = −3.05, SE = 1.47, p = 0.04). Co-occurring disorders were associated with poorer treatment response during follow-up. Results were generally consistent with a previous study of the predictors of response to ERGT. The findings provide further support for the utility of this treatment across a range of BPD patients, including patients with severe DSH and BPD.